1. Field of the Invention
The present invention relates to a detection device, particularly to an overcurrent detection device.
2. Description of the Related Art
With the prevalence of IC technology, CMOS (Complementary Metal Oxide Semiconductor) is also extensively used in various electronic elements, such as the Class-D audio power amplifier. The Class-D audio power amplifier is a high-efficiency amplifier outputting only two states (1 and 0) and usually used to drive a high-load speaker. As the Class-D audio power amplifier has very high energy conversion efficiency, it has been widely used in portable electronic products and can reduce the power consumption of portable electronic products. Thus, the standby time is prolonged, and the portability of electronic products is increased.
Refer to FIG. 1 for a conventional overcurrent detection device. A common power amplifier uses a current detector to detect the load current. When the current is over a given value, a protection circuit is triggered. Such an architecture usually needs a comparator 10 and a detection resistor 12. The comparator 10 receives the voltages at two terminals of the detection resistor 12 as the input signals and outputs a voltage signal to trigger a protection circuit.
In a class D power amplifier the audio signal is a digital signal and the conventional current detector can no longer be applied. Therefore the present invention proposes an overcurrent detection scheme, which achieves overcurrent detection by applying digitalized audio signal as control signal. Therefore, the present invention proposes an overcurrent detection device, which detects the overcurrent of the load through digitalized audio signal.